The term “probiotic” is generally used to refer to live microorganisms that provide health benefits or other positive effects when administered (e.g., by ingestion of a probiotic-containing food or dietary supplement). Probiotics may benefit a host directly, e.g., by excreting compounds that interact with the host's gastrointestinal system or by expressing useful enzymes that are absent from or insufficiently expressed by the host. Probiotics may also benefit the host indirectly by interacting with other gut flora in a manner that has a beneficial effect on the host, e.g., by displacing pathogenic bacteria. The precise nature of these interactions is often poorly understood due to the complexity of the gastrointestinal system and the gut microbiome. However, the probiotic nature of a microorganism can be evaluated based on the detection and measurement of its effects on a host regardless of whether the precise mechanism underlying the effects remains unknown.
In recent years, probiotics have emerged as a promising target for therapeutics and dietary supplements intended to promote positive gastrointestinal health and other benefits. Probiotic microorganisms have been identified in various genera, including Lactobacillus, Bifidobacterium, Propionibacterium, Escherichia, and Saccharomyces, with Lactobacillus strains being the most well characterized and commercial significant probiotics.
Traditionally, probiotics suitable for human consumption have been confined to fermented foods and dairy compositions (e.g., miso, tempeh, kefir, buttermilk, cheese, and yogurt), which provide an environment suitable to allow a sufficient amount of the probiotic bacteria to survive during typical storage conditions. More recently, dietary supplements (e.g., tablets, sachets and other delivery vehicles) have been developed which are suitable for at least some probiotics. However, survivability concerns limit the widespread use of many probiotics. In particular, many of the currently known probiotics cannot survive high temperatures for extended periods of time, substantially limiting the types of foods and supplements that may be used as a delivery vehicle for these probiotics.